Theoretical and Experimental Investigation on Laminar Boundary Layers Under Cnoidal Wave Motion
Theoretical and Experimental Investigation on Laminar Boundary Layers Under Cnoidal Wave Motion
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DOI：
10.1142/s0578563498000066
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发表时间：
1998-03
影响因子：
2.4
通讯作者：
Hitoshi Tanaka;B. Sumer;C. Lodahl
中科院分区：
文献类型：
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作者：
Hitoshi Tanaka;B. Sumer;C. Lodahl
给出了椭圆波作用下层流边界层的解析解。由于解是用傅里叶级数展开而不是椭圆函数表示的，因此可以很容易地计算边界层中的速度和底摩阻力。根据目前的理论，随着Ursell数的增加，底部边界层的速度、底部剪应力和边界层厚度等特征与正弦波边界层下的边界层特征有很大的不同。其中，底部剪应力随时间的变化是与纯谐边界层最明显的区别之一。用热膜传感器直接测量了底部剪应力，并与现有理论进行了比较。
An analytical solution is derived for a laminar boundary layer under cnoidal waves. Since the solution is expressed in terms of Fourier series expansion instead of elliptic functions, computation of velocity and bottom friction in a boundary layer can be made very easily. According to the present theory, the characteristics of the bottom boundary layer, such as velocity, bottom shear stress, and boundary layer thickness, show considerable differences from those under sinusoidal wave boundary layers with the increase of the Ursell number. Among these, one of the most distinct differences from purely harmonic boundary layers can be found in the time-variation of the bottom shear stress. A direct measurement of the bottom shear stress is made by using a hot-film sensor to compare with the present theory.